Well, uh, first they have to *find* a barge and then find something to move it with before they can really do anything about either.
yanno... ROMANS somehow managed such feats of engineering in hostile land under combat conditions using musclepower alone.
Yesterday's report was that the Mississipi is not navigable and may not be for six months. They are not even sure where the river will run south of New Orleans after all this flooding subsides. That is assuming that it does in the areas south and east of the city.
alternative:
use freight containers.
hack the tops off, tar the door-ends, load them with some ballast, air-drop 'em into position using tractors or baots with guy-lines to keep 'em stable, then air-drop more ballast in them and sink them in place.
there are hundreds of freight containers available for use over on the Jackson Avenue docks - the HQ yard of Coastal Cargo Inc has more than enough all on its own to do the job.